Today is September 15 meaning members of the LEGO VIP club (and really, why aren’t you?) can now purchase 75159, the new LEGO Death Star, and also 10254, the Winter Holiday Train. The sets will be available for non-VIP buys on October 1.
If you’re willing to wait a little bit, and risk not having one of these sets “right now” I’d recommend waiting until October 1. Starting October 1, LEGO is doing a double VIP points promotion for which both of these sets are eligible. You’ll get 2x the usual points, plus the October free set, Holiday Countdown Calendar (40222), when you buy.
Considering the USD $500 price tag on the Death Star, you would get a LOT of points there, and be able to get even more sets when you redeem them.